Heavy-duty electrode holder



June 22, 1948. N. A. BIRCH HEAVY DUTY ELECTRODE HOLDER Filed Aug. 18, 1945 NEIR MAN A E1 1R :5,

been experienced when employing Patented June 22, 1948 UNITED STATES PATENT ,OFFICE HEAVY-DUTY ELECTRODE HOLDER ..Norman A. Birch, Mahwah, N. J. Application August 18, 1945; Serial No. 611,437

2 clams. ((51. 2197-3).

(Granted under the act of ,March 3, 1883, as

amended April 30, 1928'; 3700. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon. V

This invention relates to a heavy duty electrode holder designed for use with. currents of the order of 500 amperes or more. .In the manufacture of certain ordnance items, welding operations require heavy currents if productionat a desired rate is to be maintained. In using. holders heretofore available, considerable trouble has currents greater than 300 amperes owing to the heating of the holderswhich greatly shortened the life thereof and required frequent replacements. .It is an object of the'present invention to provide an electrode holder so designed as to reduce heating therein to a minimum. It is a further object of the invention to provide a holder which is .light I inweight so that undue fatigue of the'operator is I avoided. It is another object of the invention to provide a holder'the electrode gripping mechanism of which can be manipulated by one hand to facilitate the insertion of electrodes and the removal of residue ends thereof. According to the present invention an electrode holder is provided having the above-mentioned qualities as well as mechanical simplicity and ruggedness. For a more complete understanding of the invention, reference may be had .to the following description of an embodiment thereof and to the drawing of which:

Figure l is a side elevation of an electrode holder embodying the invention. I

Figure 2 is a sectional view of the same-on a vertical longitudinal plane. I

Figure 3 is a sectional View of the conducting handle member. f

Figure 4 is an end elevation of the conducting sleeve.

The electrode holder illustrated in the drawing comprises a cylindrical handle member H] of lowresistance metal such as brass or copper having a bore 12 in the rear end thereof to receive the end of an insulated electric cable 14 by which current is supplied to the electrode. The skinned end of this cable is preferably soldered into the bore I2 to provide a good electrical connection which will carry heavy currents without excessive heating. For the same reason the Wall of the member Ill around the bore I2 is preferably of considerable thickness. The member also has a bore 16 extending in from its forward end, the outer end portion of this bore being screwthreaded as at l8 for threaded engagement with the rear end portion :ofa tubular sleeve 2 0. of

I copper or otherlow-resi-stancemetal. The area of contact between the thread faces of the sleeve 29 and the handle member In is considerable and these 'face's a'r' strongly pressed together so -that undue heating at the. threaded joint is avoided. v When the sleeve 20 isas'sembled with the member ill, afiange 22 on the sleev'eand the forward end of the. member In gripfbetween'them a spatter shield which comprises a radially extending disc H 24 of insulating fibre material reinforced by washers ZGand 28 on its opposite faces.

Slidable in the/sleeve is a pusher rod or plunger 33 which is of substantiallysmaller diameter than the interior diameter of the sleeve 20.. This plunger is provided with a transverse V notch 32 atfits for'wardflend'; the trough of the V being 'alignedwitha'pair of holes 34 through the wallsfof the sleeve 20 whichare adapted to receive anTelectrode. For the'insertion of an electrode the plunger '30 must be retracted sufl'icientlyIto-clear the holes 34. After the electrode ha peed: inserted through the holes 34 the plunger Sit-is pressed forward 801' that its outer or forward end engages the electrode in the notch -32 andpressesit firmly againstthe side edges'of the hol s so magma electrical contact is had .betweenthesleeveill and the electrode. In order s-o td maintain firm pressure between the electrode and the edges of the holes 34,a helical spring 36 is seated in the bore I 6 of the handle member 10,

. the forwardend of this spring bearing against an enlarged end portion 38: of the plunger 30. bolt 40 extends through a transverse bore in the rear end portion 38 ofithe plunger 30 and also u through a pairof aligned slots 42 in the walls of the member Ill. These slots afford limited longiudinaimcvem tthe. er 30 w enable the forward end thereof to clearthe holes 34.

For the retraction of the plunger 30 a cam lever M is provided. This may be made of a single piece of heavy sheet steel out to shape and bent to form a pair of parallel elements having cam edges 45 bearing against the washer 25 of the shield. The cam lever 44 has an extension 46 which serves as a grip and is adjacent to the handle in so that the handle and grip can be grasped by one hand of the operator and may be squeezed to retract the plunger 30. This leaves the other hand of the operator free to insert or remove an electrode. The parallel elements of the cam lever are provided with aligned holes through which the bolt 40 extends so that this bolt acts as a pivot pin for the cam lever 44. For the protection of the operators hands the grip portion 46 of the cam lever is preferably taped. The brass handle member I is surrounded by insulation in the form of a fibre jacket or casing 50 which is preferably provided with a number of ventilation holes 52, a pair of diametrically aligned slots which register with the slots 42 in the wall of the member ID, a slot 54 in the forward end for the purpose hereinafter described, and a hole opposite the slot 54 which registers with a hole 56 through the threaded portion of the wall of the member ID. The hole 56 is adapted to receive an Allen screw 58 which enters a recess or hole in the rear end portion of the sleeve 26 to lock the sleeve in its assembled relation with the member It). It is necessary to prevent relative angular movement between the sleeve 26 and the member ID and also between the plunger 3!] and the member ID so that the holes 34 in the sleeve will be maintained in alignment with the end groove 32 in the plunger. The pivot pin 46 serves to prevent relative angular movement between the plunger 30 and the member I6.

Opposite the set screw 58 a coupling assembly 60 for an air supply pipe line 62 is inserted through the slot 54 of the insulating sheath 50 and secured in a hole 64 in the member [0 which registers with a hole 66 through the sleeve '20 to admit air or other coolant from the pipe 62 into the interior of the sleeve 20. The use of an air stream may not be necessary when relatively low amperages are employed but will usually be found desirable when high amperages of the order of 500 or more are employed. The stream of air entering the interior of the tool through the pipe 62 and the hole 66 is divided, a portion flowing out through the slots 42 which are to the rear of the hole 66, the rest of the air stream flowing forward in the clearance between the sleeve 20 and the plunger 39 and escaping through the holes 34, the diameter of the holes 34 being substantially larger than the electrode itself. In order to maintain a uniform clearance between the sleeve and the plunger, the latter may be provided with four lugs near the forward end thereof, the extreme diameter of the plunger through these lugs being slightly less than the interior diameter of the sleeve 20. The air stream flowing out through the holes 34 thus provides a counter current cooling stream which prevents excessive heat flow from the electrical end of the tool to the handle thereof.

The forward end of the tube 20 is closed by a copper plug 12 which is driven into the end of the tube and is brazed therein. This plug is centrally drilled and tappedto receive a. screw 14 by which a fibre insulating cap 16 is secured to the forward end of the tool so as to avoid undesirable short circuit contacts between live elements of the tool and metal objects near the work.

I claim:

1. An electrode holder comprising a tubular sleeve of low-resistance metal having holes near its outer end to receive an electrode transversely therethrough, a handle member of low resistance metal secured to the inner end of said sleeve with a good electrical connection, an insulating sheath surrounding said handle member, a shield extending radially from said sleeve at the forward end of said handle member, aplunger slidable in said sleeve to press against an electrode extending through said holes, a spring seated in said handle member and pressing against the inner end.- of said plunger, and means operable by one hand to retract said plunger, said last mentioned means including a cam lever pivotally secured to said plunger near the inner end thereof, one end portion of said lever being a grip element extending adjacent to said handle member and adapted to be manually pressed toward said handle to rock the lever on its pivot, the other end portion of said lever being a cam element movable against said shield by rocking of the lever to force said pivot and plunger rearward.

2. An electrode holder comprising a metal handle member having a bore extending into its forward end, a tubular metal sleeve screw-threaded into the forward portion of said bore, a spring seated in said bore, a plunger slidable in said sleeve having an enlarged rear end portion pressed by said spring against the rear end of said sleeve, a pivot pin passing transversely through said enlarged portion of the plunger and the walls of said handle member, said handle member having aligned longitudinal slots in opposite walls thereof for said pin whereby limited movement of said pin in the direction of the axis of the handle member is permitted, a radial shield surrounding the sleeve at the forward end of the handle member, and a cam lever rockably mounted on said pin, said lever having a cam portion bearing on said shield and adapted to force said pin rearward when the lever is rocked.

NORMAN A. BIRCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

